Recently, electric operating machines having a motor that drives a rotary blade (for example, electric lawn mowers) attract attention and are increasingly used. Using electric power as power source, electric operating machines (lawn mowers) are quiet, discharge no exhaust gas, and excellent in running cost.
For example, Patent Literature 1 discloses an electric lawn mower having adjustable motor rotation speed. This electric lawn mower has a converter to change the voltage applied to the motor so as to change the motor rotation speed. Then, the blade rotation speed can be changed according to the lawn grass to mow or the lawn shape. Electric driving produces low driving noise.